iOS 7 二维码的生成

    //二维码生成

    //UIImageView *theImageView = [[UIImageView alloc]init];
    //[self.view addSubview:theImageView];

    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [filter setDefaults];
    NSData *data = [@"hello worold!" dataUsingEncoding:NSUTF8StringEncoding];
    [filter setValue:data forKey:@"inputMessage"];

    CIImage *outputImage = [filter outputImage];

    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef cgImage = [context createCGImage:outputImage
                                       fromRect:[outputImage extent]];

    UIImage *image = [UIImage imageWithCGImage:cgImage
                                         scale:1.
                                   orientation:UIImageOrientationUp];

    NSLog(@"image QRCode : %@",NSStringFromCGSize(image.size));
    // Resize without interpolating
    UIImage *resized = [self resizeImage:image
                             withQuality:kCGInterpolationNone
                                    rate:5.0];

    NSLog(@"%@",NSStringFromCGSize(resized.size));

    UIImageView *theImageView =[[UIImageView alloc]initWithImage:resized];
    theImageView.frame = CGRectMake(100, 200, 100, 100);
    [self.view addSubview:theImageView];

    CGImageRelease(cgImage);

　　由于生成的二维码和图片非常小，所以使用方法放大了5倍

//Resize image

- (UIImage *)resizeImage:(UIImage *)image
             withQuality:(CGInterpolationQuality)quality
                    rate:(CGFloat)rate
{
	UIImage *resized = nil;
	CGFloat width = image.size.width * rate;
	CGFloat height = image.size.height * rate;

	UIGraphicsBeginImageContext(CGSizeMake(width, height));
	CGContextRef context = UIGraphicsGetCurrentContext();
	CGContextSetInterpolationQuality(context, quality);
	[image drawInRect:CGRectMake(0, 0, width, height)];
	resized = UIGraphicsGetImageFromCurrentImageContext();
	UIGraphicsEndImageContext();

	return resized;
}

　　生成的结果：